Mandayona is a municipality in the province of Guadalajara, within the autonomous community of Castile-La Mancha, Spain. It lies in the central part of the country, in the region historically known as Castile.
According to the 2004 census conducted by the Instituto Nacional de Estadística (INE), the municipality had a population of 405 inhabitants. This figure reflects the small, rural character typical of many municipalities in the province of Guadalajara.